Des Moines Water Works' nitrate lawsuit filed

The Des Moines Water Works said Monday it had filed a long-awaited lawsuit against trustees of three surrounding county drainage districts for damages it said it has incurred as a result of nitrate pollution in Des Moines drinking water.

The three counties, Sac, Buena Vista and Calhoun, engaged in discharge of nitrate pollutants into the Raccoon River, and failed to obtain a National Pollutant Discharge Elimination System permit in violation of the Clean Water Act, the suit said.

The suit asks the districts to comply with CWA and pay damages to the utility for nitrate discharges, legal fees and civil penalties.

"Des Moines Water Works' mission is to provide safe, abundant and affordable water to our customers," Bill Stowe, Water Works' CEO said in a statement. "In order for Des Moines Water Works to continue to meet its mission and protection of the state of Iowa and the United States from further environmental and health risks, the discharge of nitrate from drainage districts must be addressed."

Des Moines Water Works serves about 500,000 Iowans. It has spent about $540,000 to operate its nitrate removal facility continuously for 97 days in December, 2014, which it said was "unprecedented in the winter months."

In addition, the utility said it had previously spent about $900,000 to control nitrates in 2013, and is planning capital investments of $76-183 million for new denitrification technology.

The utility says the major source of nitrates in the Raccoon River watershed is the artificial subsurface drainage system infrastructure maintained by the Sac, Buena Vista and Calhoun County drainage districts.

Recent upstream water monitoring at 72 sample sites in Sac County has shown nitrate levels as high as 39.2 mg/L in groundwater discharged by drainages districts, the utility said. By law the maximum contaminate level in finished drinking water for nitrate is 10 mg/L.

According to the Des Moines Register, more than 2 million acres, mostly farmland, drain into the Raccoon River, which, in part, supplies the Des Moines area with drinking water. Man-made tiles are installed on about 78% of that land, the Register noted.